<?php
$atributos = array('type' => 'hidden', 'name' => 'txt_id', 'id' => 'txt_id', 'value' => $id_unidad);
echo form_input($atributos);
?>

<div class="form-group">
  <label class="col-sm-3 control-label">Logo</label>
  <div class="col-sm-5"><?=$this->extras_form->examinarButton();?></div>
</div>